1. Field of Invention
This invention relates to the sequential addition to the influent raw waste water upstream of the primary clarifier or sedimentation tank: first, a salt of a water soluble bi- or tri-valent metal, or mixtures thereof; second, fly-ash, and third, a water soluble cationic surface active polymer composition comprising a polyether amine to improve the efficiency of the primary clarifier in raw waste water clarification.
2. Information Disclosure Statement
Numerous attempts have been made by the prior art to lower biological oxygen demand and chemical oxygen demand, to reduce turbidity, to decrease residence time in the primary clarifier, to remove colloidal material and to reduce the volume of sludge in waste water treatment while maintaining the efficacy of the treatment process.
One prior art process utilizes high molecular weight polyvinyl amine hydrochloride alone or in combination with alum or ferric chloride to serve as a flocculating agent.
Another prior art process teaches consolidating a low solids content liquid sludge via adding weighting agents such as coal ash, limestone powder or cement to the sludge before, during or after the addition of agglomerants.
A further process teaches a method for improving the de-watering of aqueous suspensions of organic solids by adding a high molecular weight, water soluble, anionic polymer prior to the addition of the cationic polyelectrolyte to aqueous suspensions, including municipal waste sludges, for example, raw activated (obtained by aerobic biological oxidation of raw sewage) and digested (obtained by anaerobic biological oxidation of raw sewage) sewage sludges. A preferred species of anionic polyelectrolyte is a high molecular weight homopolymer of an alkali metal salt of vinylbenzene sulfonic acid. Cationic polyelectrolytes used in the above invention are water-soluble, synthetic, organic polymers characterized as containing in or attached along the polymeric chain a plurality of amino, imino or quaternary ammonium groups.
Another prior art process teaches an improved process for the clarification of coal wash water by the sequential addition of a critical amount of both anionic polymer followed by a cationic polymer to the aqueous suspension.
Another prior art method teaches a process for de-watering of petroleum containing sludges with recovery of the oil by adding finely divided additives (ash, coal, sand) and homogeneously dispersing the additives in the petro-containing sludge then adding to the mixture an organic flocculent and allow for gravity filtration which removes a greater part of the sludge water. The de-watered sludge mixture is then treated with aluminum or iron salts and the mixture is substantially de-watered by pressure filtration.
Another prior art process teaches the removal of color from papermill waste waters, by adding the polyethylene imine with a molecular weight of at least 300 in an amount sufficient to form a complex solid of the imine with the color bodies in the waste water which is filterable.
A further prior art process teaches the de-watering of sludge without adding lime, ash or sand by adding an organic flocculent to the sewage sludge, mixing, holding for about 5 minutes to insure the formation of flocculated sewage sludge particles and allowing flocculated sewage sludge to filter by way of gravity and passing gravity filtered flocculated sewage sludge particles to a chamber filter process without using shear forces (reciprocating diaphram pumps or electric screw pumps are used) then pressure filtering the gravity filtered flocculated sewage sludge at a pressure of 10-15 bar using a chamber filter press.
An early prior art process teaches a method of removing impurities from water by adding an emulsion of a saponified resin to the impure water, then adding an acid acting chemical, such as alum, which causes the emulsion to coagulate and any impurities adhere to the coagulate which separates from the water.
Another prior art method teaches a process to de-colorize pulp mill bleach plant caustic extraction effluent by utilizing a primary or other sludge from a pulp and papermill. The sludge is acidified and mixed with the effluent, allowed to stand and then raised to at least a neutral pH which causes the precipitation of most of the color in the effluent which may be removed by conventional clarification techniques.
Another prior art method is drawn to a method for automatically changing the rate of addition of clarifying chemicals as the level of terbidity of incoming water changes.
Another prior art method is drawn to a method for removing colloidal and/or finely divided insoluble material by adding a floc forming material, for example, alum, to the water in order to form a floc, then adding a filter aid material, then adding a cationic polyelectrolyte; thereafter, the entire suspended matter is removed by simple filtration. The filter utilized is a vacuum or suction filter. The filter aid material is the commercially available filter aid material such as diatomaceous silica, expanded perlite, or other filter aids or mixtures of the same. The cationic polyelectrolytes encompassed by the invention include a hydrophilic alkylene polyanine polyfunctional halohydrin resulting from the condensation of an alkylene polyamine and a polyfunctional halohydrin in aqueous solutions and sold under the trademark NALCO 600. Another example is a branch chain polyelectrolyte containing sulfonium active groups sold under the trademark UCAR C-149.
Therefore, it is an object of this invention to provide a process which overcomes the aforementioned difficulties of the prior art processes and provides an improvement which is a substantial contribution to the advancement of the waste water treatment art.
Another object of the present invention is to provide a process for increasing the efficacy of the primary clarifier thereby decreasing residence time in the primary clarifier also referred to as a sedimentation tank.
Another object of the present invention is to provide a process for increasing the efficacy of the primary clarifier which increases the capacity or flow through rates of a waste treatment plant using a sedimentation tank or primary clarifier.
Another object of the present invention is to provide a process for increasing the efficacy of a primary clarifier by lowering biological oxygen demand and chemical oxygen demand of the influent raw waste water.
Another object of the present invention is to provide a process for increasing the efficacy of a primary clarifier by utilizing a process which does not require a filtration step to increase the efficacy of a primary clarifier.
Another object of the present invention is to provide a process for increasing the efficacy of a primary clarifier by decreasing the concentration of suspended solids of the influent raw waste water.
Another object of the present invention is to provide a process for increasing the efficacy of a primary clarifier by decreasing turbidity by removing colloidal material from the influent raw waste water.
Another object of the present invention is to provide a process for increasing the efficacy of a primary clarifier by reducing the volume of sludge or increasing the density of the sludge collected in the primary clarifier.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the invention. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.